Amphibian eggs contain, before fertilization, a large quantity of RNA synthesized by the maternal genome which is utilized for protein synthesis during early development. The program of utilization of this maternal mRNA will be investigated during early development in embryos of Xenopus laevis. Nucleic acids will be synthesized that are complementary to maternal and embryonic RNA populations. These complementary nucleic acids will be hybridized to total RNA and polysomal mRNA to determine when the RNA sequences stored in the egg appear on polysomes. The second phase of this project involves the sequencing of non-translated regions of the maternal and embryonic RNA populations in a search for possible binding sites for regulatory proteins. Methods are described to investigate the sequences present preceeding the signal for the initiation of protein synthesis and those following termination of protein synthesis. These sequences should be those that are recognized by factors that control protein synthesis and the addition of poly(A) to mRNA. This information should contribute to te understanding of possible post-transcriptional control elements operating during development.